Applying a metal layer to a surface of a doped semiconductor material, e.g., a layer enriched or depleted of carrier charges, creates a contact region having properties comparable to a p-n junction in a semiconductor material. The common name for this metal-semiconductor contact region is a Schottky diode. The ability of Schottky diodes to substantially restrict current flow to one direction is a property heavily relied upon in the manufacture and design of integrated circuits. When forward biased, a Schottky diode is in an “on” state and current flows through the diode. When the diode is reverse biased, a Schottky diode is in an “off” state and ideally will not allow current to flow. However, Schottky diodes are generally not ideal and thus typically experience a small amount of reverse leakage current, which flows back through the diode when the diode should not be conducting current.
Reverse leakage can be detrimental to the performance of a circuit and may result in a loss of power in the circuit. A portion of the reverse leakage current can arise from the physical junction interaction between the Schottky metal, or Schottky barrier, and an adjacent semiconductor material. Regardless of its source, reverse leakage current usually induces undesirable characteristics in the operation of an electronic device, such as reducing efficiency.
The breakdown voltage of a Schottky diode is generally the maximum amount of reverse voltage that may be applied to the diode before the diode begins to breakdown and experiences an exponential increase in reverse leakage current. The ability to apply a greater reverse voltage to a Schottky diode without the diode breaking down (greater breakdown voltage) enables the diode to be integrated into circuits for higher voltage applications, e.g., applications having voltage levels that exceed a few volts.